With everything, including Raspberry Pi Pico, whizzing around at high speed, you may well be wondering how it’s powered without quickly causing a tangle of wires. “In order to leave a beautiful afterimage, a speed of ten revolutions or more per second is required,” reveal HomeMadeGarbage.ĭiscovering that “the I/O of Raspberry Pi Pico can run very fast”, they’ve managed to spin the arm at up to 960rpm while displaying an image at 1000 frames per rotation. In the software, written in C, the time taken for one rotation is divided by 1000 to sync the blinking of LED patterns stored in a graphics array. HomeMadeGarbage say that they improved detection reliability by inserting “a filter and a Schmitt trigger between the reflectance sensor and Pico to prevent chattering.” The arm is spun at high speed by a Mabuchi RS-540SH motor, as commonly used in remote-control cars.Įach rotation is detected using a reflectance sensor on the arm and a small white marker underneath. The POV Display uses two different PIO state machines (from the eight available on the chip) to control, in parallel, a pair of super-bright 24-LED APA102 (aka DotStar) strips on its rotating arm. This offers a faster way of outputting bit-banged data (even video) to non-standard devices with a deeper level of control, without tying up the main processor. The makers tell us that, after creating a similar project using Sony’s considerably more expensive Spresense board, they were inspired to try it with Pico, as they were “very surprised at the parallel high-speed operation of PIO.” The latter is the unique Programmable Input/Output feature of Pico’s RP2040 chip that enables the use of custom communication protocols in addition to the built-in I2C and SPI. This is just what Japan-based family team of makers HomeMadeGarbage have done for their POV Display, even spinning a Raspberry Pi Pico around with the LED strips. Modifying the PWM duty ratio, one is able to obtain a constant velocity of the motor.By rotating a strip of LEDs at high speed and syncing their blinking patterns, it’s possible to create the illusion of a still or moving image. By measuring the time between each signal, one is able to find the rotational speed. The Tachometer provides 2 signals per rotation. In parallel, the motor control is also implemented (not just yet, I’ll provide updates after we finish working on it). The module will also work as a slave (awaiting connections), with the HC-05 being the master (actively connect to the slave). Jumper 4 on the PmodBT will be shorted to ensure this. Therefore, the baud rate of both modules must have the same value (9600 in this case). #Persistence of vision 3d clock Bluetooth#The positions of the snake body and the food are transmitted via Bluetooth to the Arduino. When hitting the edge, the snake will come back from the other side. As it eats the food, it increases in size. The snake moves around using the buttons on the Basys. Using the Vivado IDE, we implemented a simple snake game in VHDL. #Persistence of vision 3d clock software#See also Memory Video Game Using Atmel Mega32 Step 3: Logic Part Software This can be tweaked by gluing counterweights. Take care, as the ruler has to have the center of mass close to the center of rotation, else strong vibrations will occur. On the ruler we mounted the electronics using a hot glue gun. The Arduino and Bluetooth module are mounted on a custom-made PCB, with connectors and pin headers used for convenience.įor the mechanical part, we “transformed” a computer fan into a… ruler fan. If possible, try not to light too many LEDs at the same time (or do it at lower power), as the 7805 provides a maximum of 1A, otherwise there may not be enough power for the Arduino. #Persistence of vision 3d clock full#WARNING: a LED at full power consumes 60mA. After passing through a voltage regulator, the regulated 5V will supply the LEDs, the Arduino and the Bluetooth module. The board is also connected to the PWM and Tachometer pins of the fan, in order to provide a speed control (I will come back with updates after its implementation).įor the functional part, we have the electronic and mechanical implementation.įor the electronics, we provided a 9V battery as a supply source. For the logic part, the Bluetooth module is inserted in the Pmod socket A of the FPGA board.
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